Lightning arrester



D 1969 v V s. s. KERSHAYW, JR I 3,484,863

L IGHTNING ARRESTER Filed Nov. 17, 1967 2 Sheets-Shet 1 .Z'A/VEA/TOR. Stanlqy 5. Kens/mu,:/iz

M WM Dec. 16, 1969 s. s. KERSHAW, JR

LIGHTNING ARRESTER 2 Sheets-Sheet 2 Filed Nov. 17, 1967 F D Z Z J W. 5 M n m o United States Patent O US. Cl. 317-61 12 Claims ABSTRACT OF THE DISCLOSURE A high voltage lightning arrester including a hollow insulating housing, a plurality of lightning arrester modules arranged in a column within the housing, each pair of adjacent modules being provided with coacting end assemblies which are loosely coupled and slideably engageable along an inclined surface so that adjacent modules will move in opposite lateral directions when lowered into the housing, wherein rubber bumpers carried by each end plate will compressively engage the internal surface of the insulating housing to brace the module against the housing wall so as to prevent movement of the module components during shipment and installation.

BACKGROUND OF THE INVENTION High voltage lightning arrestors of the station class are generally formed of a plurality of endwise connected lightning arrester modules which are enclosed in a relatively elongate, hollow insulating housing. Each module may include a plurality of spark gap assemblies and nonlinear resistance elements which are joined in a unitary assembly with the number of such modules determining the voltage rating of the device.

In order to prevent damage to the active lightning arrester components during shipment and installation, it is necessary to prevent contact between are elongate assembly of lightning arrestor modules and the insulating housing. Preassembled bracing devices provided for this purpose are not wholly satisfactory, however, because the inside diameter of the porcelain insulating housings, of the size used for station arrestors, may have tolerances in the order of one-half inch. It will also be appreciated that it is extremely difficult to provide bracing for the assembly once it has been inserted into the insulating housing.

It is an object of the invention to provide means for supporting active lightning arrester components within an elongate insulating housing.

Another object of the invention is to provide means for bracing lightning arrester component assemblies against contact with the internal Wall of an insulating housing and which are not affected by cariations in the internal diameter of the hollow insulating housing.

A further object of the invention is to provide means for bracing lightning arrester component assemblies within an elongate insulating housing, wherein insertion and removal are not impeded.

SUMMARY OF INVENTION A high voltage lightning arrester comprising a plurality of lightning arrester modules disposed in an insulating housing, each module comprising a plurality of lightning arrester components mounted between a pair of end elements in a unitary assembly, adjacent end elements being loosely coupled and operative to move adjacent modules in opposite directions and into engagement with the housing wall upon insertion and away from the wall upon insertion and away from the wall upon removal from the housing.

3,484,863 Patented Dec. 16, 1969 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view with parts broken away of a lightning arrester incorporating the bracing means according to the invention;

FIG. 2 illustrates a module assembly component of the lightning arrester illustrated in FIG. 1;

FIG. 3 is a view taken along lines 3-3 of FIG. 1, with parts broken away;

FIG. 4 is a view taken along lines 4-4 of FIG. 3; and

FIGS. 5 and 6 illustrate the interaction between the end bracing element of the lightning arrester modules.

DESCRIPTION OF THE PREFERRED EMBODIMENT A lightning arrester 10, incorporating the instant invention, is shown in FIG. 1 to include a hollow, generally cylindrical housing 11 of a suitable insulating material, such as porcelain or glass, and which is closed at its upper and lower ends by conductive end fittings 12 and 13, respectively. As those skilled in the art will appreciate, each of the end fittings 12 and 13 may be provided with a recess 14 for receiving the ends of the insulating housing 11 and each may be affixed to its respective end in a sealing relation by means of a suitable cementing compound 15. The housing 11 is provided with a central bore 16 for receiving a plurality of lightning arrester modules 17, each of which includes a plurality of nonlinear resistance elements 18 and spark gap assemblies 19.

While each of the lightning arrester modules 17 is a complete unit in itself and may be used as such, those skilled in the art will appreciate that, in high voltage station type arresters, a plurality of such units, as may be required to provide the desired voltage rating may be arranged in a series relation within the elongate housing 11.

The resistance elements 18 may have a generally cylindrical configuration and may be composed of a material such as silicon carbide, which has a nonlinear voltage characteristic, whereby it presents a low resistance to surge currents and a high resistance to the normal power current of the system. The resistance elements 18 and the spark gap assemblies 19 may be coaxially arranged in a vertical column and are electrically connected in a series circuit relation, in a manner which is not shown, but which is well known in the art. Those skilled in the art will also appreciate that grading resistors, not shown, may be connected in shunt with the spark gap assemblies 19.

As will be discussed in greater detail hereinbelow, the column of resistance elements 18 and spark gap assemblies 19 may be secured by means of insulating tie rods 20 which may be pinned at each end to one of a pair of end assemblies 21. Prior to the pinning of the tie rods 20, the column of resistance elements 18 and spark gap assemblies 19 may be placed in endwise compression in any manner well known in the art.

A metallic compression spring 23 may be disposed between the upper end cap 12 in the upper end assembly 21 to firmly hold the column of lightning arrester modules against a spacer member 24 which is disposed between the lower end assembly 21 and the lower end cap 13. As those skilled in the art will also appreciate, conductive shunt members, not shown, may interconnect the end caps 12 and 13 and the upper and lower lightning arrester modules 17 to shunt the spring member 23 and the spacer member 24.

The details of the spark gap assemblies 19 form no part of the instant invention and, accordingly, will not be discussed in detail. As an example of the spark gap assembly which could be employed in the instant lightning arrester, reference is made to US. Patent 3,242,376, is-

sued Mar. 22, 1966, and assigned to the assignee of the instant invention.

It will be sufiicient for purposes of understanding the invention to state that the spark gap assemblies 19 normally isolate the line conductor 26 connected to the upper end of the cap 12 from the grounded lower end cap 13. Upon the occurrence of a voltage surge, however, the spark gap assemblies 19 break down and conduct surge current carried by the line conductor to ground. Because of the nonlinear resistance characteristic of the elements 18, they readily pass the surge current and then restore the system to its normal operating condition after the voltage across the device is returned substantially to the line voltage of the system, by limiting the flow of current to a value which is insufficient to sustain the arcing in the spark gap assemblies 19.

As seen particularly in FIGS. 2-6, the end assemblies 21 each include an end plate 30 which may be secured by screws 31 to one side of a relatively fiat, generally rectangularly shaped insulating support block 32. The block 32 may have apertures 33 formed in three corners thereof for receiving one end of the insulating tie rods 20 and which may be secured therein by pins 34. As seen in FIG. 1 the other ends of the rods 20 are similarly secured to an identical end assembly 21 to hold the lightning arrester components 18 and 19 in the columnar module assembly 17.

The adjacent end plates 30 of each assembly 17 are disposed in an opposed relation and each has one edge shaped to correspond to its associated block 32 and a pair of legs 36 extending outwardly from the other end and toward the internal surface 16 of the housing 11. A foot 38 extends perpendicularly from each leg 36 for supporting an annular resilient bumper 39 which is suitably fastened thereto. The bumpers 39 allow resilient engagement between the end plate 30 and the internal :wall 16 of the housing 11. As seen particularly in FIG. 3, the

legs 36 of adjacent end plates 30 extend in opposite directions to engage the opposite side of the internal surface 16.

Each plate 30 has a generally V-shaped strap member 41. In this manner adjacent modules 17 are loosely conopposed plate on the adjacent lightning arrester module 17.

Each of the plates 30' and the blocks 32 are suitably cut away at 42 and 43, respectively, for receiving the apex of the strap extending from the opposite plate 30. In addition, a pin 45, which is anchored by eyelets 46, extends across the cutaway 42 of each plate 30 and beneath the strap 41 extending from the adjacent plate 30 to conple the adjacent modules 17. As seen particularly in FIGS. 4, and 6, the outer surface 47 of each strap 41 is slideably engageable with the edge 49 of the cutout 42 on the adjacent plate 30 and each pin 45 is slideably engageable with the inclined undersurface 50 of its associated strap 41. In this manner adjacent modules 17 are loosely connected along inclined surfaces.

Reference is now made to FIG. 5, which defines the limits of relative movement between the adjacent plates 30. These limits are the point of engagement between the pins 45 and the apex of the straps 41, on the one hand, as seen by full lines and, on the other, by the engagement between portions of the plates 30, as shown by phantom lines.

In addition to the plates 30 at each end of the modules 17, additional plates are provided at the upper and lower ends of the lightning arrester to provide bracing on both sides of the assembly.

In the assembly of the lightning arrester 10, the modules 17 are first coupled by passing the pins 45 on one plate 30 through the straps 41 on its associated adjacent plate 30. The assembly is then elevated, wherein the module weight causes each of the pins 45 to bottom on the apex of its associated straps as shown by full lines in FIG. 5. The assembly is then lowered into the housing 11 until the spacer 24 engages the lower end cap 13. At this point,

each of the plates 30 is still in its relatively spaced position shown in FIG. 5. As the lowering of the assembly continues, the lowermost lightning arrester module 17 begins moving toward an opposite side of the housing 11 as a result of the interaction between the inclined surface 47 and the edge 49 of its associated plate member 30. This movement will continue until the bumpers 39 on the plates at the upper and lower ends of the module engage the opposite side of the housing 11. Further lowering of the assembly will cause the next succeeding module to begin moving in the opposite direction until the bumpers 39 on its plates 30 engage the inner surface 16 on the adjacent side of the housing 11, and so on, until each of the modules is firmly braced against the inner surface 16 of housing 11.

It will thus be appreciated that a firm bracing action is obtained, regardless of variations in the internal diameter of the housing 11. In addition, a plurality of resilient braces at each side of the housing 11 is achieved throughout the housing length as the lightning arrester assemblies are lowered into position to facilitate assembly of the device.

As stated hereinabove, when the lightning arrester assembly is suspended outside of the housing 11 the weight of each module forces the plates 30 apart until the pins 45 bottom at the apex of their associated straps 41. This places the assembly in a minimum diameter condition, as shown by full lines in FIG. 5 so that the assembly may be easily lowered into the housing 11.

In a similar manner, should it be desired to remove the assembly from the housing 11, the lifting of the uppermost module 17 would bring the inclined surface 50 on the strap 41 of its lower end plate 30 into engagement with the pin 45 of the adjacent plate 30. This will cause the upper modules 17 to move away from the surface 16 and into their minimum diameter position, and so on, so that the entire assembly may be easily removed from the housing 11.

Because of the loose coupling between adjacent modules, a conductive shunt 40, shown in FIG. 1, may be provided between the end plates of adjacent modules to insure a good series circuit connection between modules.

While only a few embodiments of the invention have been shown and described, it is not intended to be limited thereby.

I claim:

1. An overvoltage protective device including an elongate hollow insulating housing, a plurality of lightning arrester modules disposed within said housing and each including a plurality of lightning arrester components mounted between a pair of end means in a unitary assembly, each of said end means including coupling means for loosely joining said modules in a generally vertical column, said coupling means being operative to produce relative movement between said modules toward alignment when in a position of maximum separation and away from alignment when in a position of minimum separation and engagement means on each end means for engaging the hollow internal surface of said housing.

2. The device set forth in claim 1 wherein each of said coupling means includes inclined surface means engageable with the coacting adjacent coupling means for producing relative lateral movement as said modules are moved toward and away from each other.

3. The device set forth in claim 1 wherein said engagement means includes resilient means engageable with the intemal housing surface.

4. The device set forth in claim 1 wherein said lightning arrester components include spark gap assemblies and nonlinear resistance elements connected in a series circuit relation, and including means for connecting said modules in a series circuit relation, and elongate means coupled to the pair of end elements associated with each module for holding the lightning arrester components together.

5. The device set forth in claim 1 wherein said end elements include a plate portion and elongate strap means extending obliquely toward the plate portion of the coacting adjacent end element, each end element having a recess formed therein for receiving the strap means of the coacting adjacent end element, and a coupling member aflixed to each plate portion and extending beneath the coacting strap means for loosely coupling said end elements.

6. The device set forth in claim 2 wherein said engagement means extends in the direction of said lateral movement.

7. The device set forth in claim 6 wherein said engagement means includes resilient means engageable with the internal housing surface.

8. The device set forth in claim 2 wherein the inclined surface means extends in a direction generally inclined at an acute angle to a plane generally normal to the axis of said housing and having a first surface portion engageable with a first portion of the adjacent coupling means when said modules are moved toward each other to produce relative lateral outward movement and a second surface portion engageable with a second portion of the adjacent coupling means when said modules are moved away from each other to produce relative inward lateral m vement.

9. The device set forth in claim 8 wherein said engagement element means extends in the direction of said lateral movement and resilient means engageable with the internal housing surface.

10 The device set forth in claim 8 wherein said end elements include a plate portion and said inclined surface means comprises an elongate strap means extending obliquely toward the plate portion of the coacting adjacent end element, wherein the opposite sides of said strap means comprise said first and second surface portions, each end element having a recess formed therein for receiving the strap means of the coacting adjacent end element to provide the first engageable portion, and a coupling member aifixed to each plate portion and extending beneath the coacting strap means for loosely coupling said end elements and to provide the second engageable portion.

11. The device set forth in claim 9 wherein said engagement element means extends in the direction of said lateral movement and resilient means engageable with the internal housing surface.

12. The device set forth in claim 11 wherein said lightning arrester components include spark gap assemblies and value elements connected in a series circuit relation, and including means for connecting said modules in a series circuit relation, said end elements including a block member for supporting said plates, and elongate means coupled to the pair of block members associated with each module for holding the lightning arrester components together.

References Cited UNITED STATES PATENTS 2,399,502 4/1946 Olsen 3176l X 3,184,634 5/1965 Kershaw 31536 3,447,118 5/1969 Ferree 317-61 X LEE T. HIX, Primary Examiner J. D. TRAMMELL, Assistant Examiner US. Cl. X.R. 174139; SIS-36 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,484,863 December 16, 1969 Stanley S. Kershaw, Jr.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 15, "value" should read valve Signed and sealed this 27th day of October 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR. 

